Bench test centres

ABSTRACT

The component testing apparatus described comprises bench test centres. A headstock and a tailstock are mounted on a base; each stock has a body in which a centre is mounted. The component, when under test, is arranged between the two centres, which are coaxial. The headstock includes a drive for rotating the component under test. A brake is also provided to stop rotation of the component at a selected position.

ilite States Ann atent 1 Feb. 12, 1974 1 1 BENCH TEST CENTRES [75]Inventor: Charles Vivian Marrett Allix,

London, England [73] Assignee: C. V. Precision Tools Limited,

Chiswick, London, England [22] Filed: Dec. 31, 1 970 21 Appl. No.:103,227

[30] Foreign Application Priority Data Jan. 6, 1970 Great Britain 672/70[52] US. Cl. 33/174 Q, 33/147 E, 33/199 B [51] Int. Cl. B23b 33/00, GOlb5/10 [58] Field of Search33/l47 E, 174 Q, 199 B; 82/28,

[56] References Cited UNITED STATES PATENTS 2,170,510 8/1939 Trible318/366 2,531,317 11/1950 Baney et a1. 33/174Q 1,868,594 7/1932 Black eta1... 82/40 2,545,852 3/1951 Kurzweil 82/33 2,829,442 4/1958 Peickii33/199 B 2,348,973 5/1944 Groene et a1. 82/28 FOREIGN PATENTS ORAPPLICATIONS 1,131,291 10/1968 Great Britain 33/199 B PrimaryExaminerLouis R. Prince Assistant ExaminerChar1es E. Phillips Attorney,Agent, or Firm-Eugene D. Farley [5 7] ABSTRACT The component testingapparatus described comprises bench test centres. A headstock and atailstock are mounted on a base; each stock has a body in which a centreis mounted. The component, when under test, is arranged between the twocentres, which are coaxial. The headstock includes a drive for rotatingthe component under test. A brake is also provided to stop rotation ofthe component at a selected position.

4 Claims, 2 Drawing Figures Patented Feb. 12, 1974 2 Shasta-Smut 1INVENTOR QHARLEa \IMAN MRREETT atented Feb. 12, 1974 3,791,039

2 Sheets-Sheet 2 MAE NTO R me sfi my ATTORNEY BENCH TEST CENTRES Theinvention relates to the testing of components, such as shafts orsimilar components, whichhave been centred at both ends, betweencentres.

In bench test centres, the component is located between two centreshoused respectively in a headstock and a tailstock. The stocks aremounted on a base which usually has a surface plate which serves as areference surface. Either or both of the stocks may be movable along thebase to adjust the separation of the centres, and the centres may beadjustable in the stocks.

In conventional practice, the contact point of a dial gauge mounted onthe surface plate is brought to bear on the surface to be checked, andthe component is rotated by hand to measure the accuracy of the surface,for eccentricity, or swash.

The present invention is based on the elimination of manual rotation ofthe component, thus enabling the inspector or operator to concentrate onthe measurement of error and to use both hands in manipulating themeasuring device in order to observe and record one or severaldimensions.

The invention provides a headstock for component testing apparatus, theheadstock having a body in which is mounted a centre and drive means forrotating a component when arranged between the centre and a furthercentre.

The drive means may comprise a motor and a transmission including a gearbox. The component may be rotated by direct friction against thecomponent, the centre being stationary or idle. An on-off switch for themotor or other drive means may cooperate with a braking device whichallowsthe operator to stop the component dead at a selected position.

For example, with an electric motor coupled to a geared speed reductionunit, an electromagnetic brake is arranged to pull off when energised,and clamp on when deenergised, the brake mechanism being an integralassembly. I

An important preferred feature is the provision of a dead stop devicewhich can stop the rotation of the work between the centres (i) at thepoint of maximum run out (departure from desired profile) as shown bythe probe or other measuring device, or (ii) when the run out exceeds apredetermined maximum which constitutes rejection of the work.

The work can be stopped at the point of maximum run out as determinedvisually by a clock or meter read out, or at any other point, bymanually switching off the power drive, which automatically applies apowerful brake to stop the drive within one revolution of the driveshaft or approximately 2 of rotation of the work. An electro-magneticbrake would be energised by the motor control. With hydraulic,pneumatic, and clockwork drives, the brake would be operatedsimultaneously with the relay controlling the supply valve, or clutchcontrolling the drive. i

For stopping at maximum run out the run out can be indicated on a meterfrom a proximity probe or mechanical contact with the work, and thismeter incorporating special contacts, and/or a trailing pointer whichwould be left behind to indicate the maximum run out obtained on thefirst revolution of the work. On the second revolution, after closing anauxiliary switch, the work is stopped at the point of maximum run out byautomatic control from the meter itself or by opening the motor switchwhen the reading of the meter reaches that of the trailing pointer.Alternatively, when the meter pointer starts to recede from a maximumposition, a sensing head could operate a relaysimultaneously to switchoff the drive and de-energise the brake coils thereby stopping thedrive.

For stopping when a predetermined tolerance is exceeded, the tolerancecan be preset on the meter by a limit contact which energises the driverelay, which in turn cuts the supply to the drive and allows the braketo operate.

The operation of the drive-controlling relay for each of the main typesof drive is preferably as follows: for .eIectro-magnetic or inductiondrive the relay when energised interrupts the supply to motor and brakecoils; for hydraulic or pneumatic drives, the relay closes a valvecontrolling the supply to the drive and the brake, or energises thebrake; for clockwork mechanisms, the relay interrupts the supply to theclutch/- brake, which stops the drive.

The invention will be described further with reference to theaccompanying drawings, which illustrate specific embodiments, by way ofexample only.

In the drawings:-

FIG. 1 is a diagrammatic side view, partly in longitudinal section, ofone embodiment of component testing apparatus according to theinvention; and

FIG. 2 is a schematic section on line II-'-II of FIG. 1, certain partsbeing omitted for clarity.

As shown in the drawings, the testing apparatus comprises a base l,'ofcast iron or pre-stressed aluminum alloy, on which a headstock 2 and atailstock stock 3 are mounted. The stocks 2, 3 house respective 4, 5which are accurately aligned with their centre-lines coincident, thecentre-lines being parallel with the machined surface 6 of the base 1.The stocks 2, 3 are located in a longitudinal tee-slot having areference edge in line with the centre-line of the centres. Thetailstock 3 is of conventional design and is slidable longitudinally ofthe base 1 by means of a tee-slot guide. The base 1 has feet 7 forhorizontal work; the apparatus can also be used vertically, when itrests on feet 8 formed on the headstock 2 and base 1.

Referring to FIG. 1, a manual or pedal operated onoff switch 9 controlsan electric motor 10 and an electromagnetic friction brake 11cooperating with a disc on the armature shaft. The motor 10 is an ACshadedpole motor with a coil wound on a nylon bobbin covered in cottontape and varnished. The motor 10 is connected to a gearbox 12 having aninput gear of Belrin,.the other gears being of case-hardened steel. Thebrake 11, motor 10, and gearbox 12, are constructed as a rigid assemblymounted in the headstock, and this assembly can be replaced easily byremoving the cover plate 15, disconnecting and withdrawing the assemblyfrom the headstock, and inserting a replacement assembly.

The gearbox 12 provides a high gearing-down so that the centre 4 can berotated at speeds of say 7, 12, 20, 50, or rev/min. It is also possibleto use a variablespeed motor. At low rotational speeds and highgearing-down, rapid braking of the motor, when the motor supply isswitched off, will produce a virtually dead stop of the output spindle16 of the gearbox 12 which extends from the headstock 2 and carries adriving drum 17. A bearing sleeve 18 coaxial with the drum l7 carries apivotable arm 19 bearing an axle 20 on which a roller 21 is rotatablymounted. The circumference of the roller 21 is a rubber ring 22 which isfrictionally engaged with the circumference of the drum 17 at all times;this frictional engagement is maintained when the arm 19 is pivoted. Theaxle 20 is urged by a torque spring 23 into a position in which theroller 21 abuts a component, such as a shaft 24 (FIG. 2), mountedbetween the centres 4, the spring 23 forces the rubber ring 22 againstthe surface of the component, so that the rotation of the driving drum17 is transmitted to the component.

FIG. 2 shows the ring 22 in contact with the surface of a shaft theprofile of which is indicated in chaindotted line at 24, the roller 21being urged in the direction of arrow A. With components of differentdiameter the arm 19 adopts a position in which the ring 22 contacts thesurface of the component; the axis of rotation of the roller 21 will liesomewhere along the chaindotted line 25. The reference edge 26 of thetee-slot is in line with the centre-line of the centre 4.

For components having parts oflarge diameter which might interfere withthe driving drum 17, the centre 4 can be extended beyond the drum 17,and the roller 21 can be provided with a pair of circumferential rubberrings, one of which contacts the drum l7, and the other of which liesbeyond the tip of the centre, where it can contact the component.

I claim:

1. Component testing apparatus comprising:

. a base,

. a headstock mounted on said base,

. an undriven centre mounted in said headstock, a tailstock mounted onsaid base,

. an undriven centre mounted in said tailstock,

Q4010 (TD f. said headstock and tailstock centres having a commoncentre-line and being adapted to support between them a component to betested,

g. a friction drive wheel,

h. means mounting the friction drive wheel for movement toward saidcommon centre-line for peripheral contact with a component mountedbetween said centres for rotating the component by said friction drivewheel,

i. drive means engaging said friction drive wheel for rotating thelatter at a component testing speed, and

j. brake means associated with said drive means and actuable to brakethe latter.

2. The component testing apparatus of claim 1 wherein said wheelmounting means comprises a pivotable arm, and spring means engages thearm for urging the wheel toward said common centre-line.

3. The component testing apparatus of claim 1 wherein said wheelmounting means comprises:

i an arm mounting the friction drive wheel at one end thereof,

l a driving shaft connected to the drive means for rotation by thelatter,

m bearing means mounting the opposite end of the arm for pivotalmovement on an axis coaxial with said driving shaft, and

n a driving drum on the driving shaft frictionally engaging the frictiondrive wheel for rotating the latter.

4. The component testing apparatus of claim 1 wherein said drive andbrake means are mounted within said headstock, and said friction drivewheel is mounted on said headstock.

1. Component testing apparatus comprising: a. a base, b. a headstockmounted on said base, c. an undriven centre mounted in said headstock,d. a tailstock mounted on said base, d. an undriven centre mounted insaid tailstock, f. said headstock and tailstock centres having a commoncentreline and being adapted to support between them a component to betested, g. a friction drive wheel, h. means mounting the friction drivewheel for movement toward said common centre-line for peripheral contactwith a component mounted between said centres for rotating the componentby said friction drive wheel, i. drive means engaging said frictiondrive wheel for rotating the latter at a component testing speed, and j.brake means associated with said drive means and actuable to brake thelatter.
 2. The component testing apparatus of claim 1 wherein said wheelmounting means comprises a pivotable arm, and spring means engages thearm for urging the wheel toward said common centre-line.
 3. Thecomponent testing apparatus of claim 1 wherein said wheel mounting meanscomprises: k. an arm mounting the friction drive wheel at one endthereof, l. a driving shaft connected to the drive means for rotation bythe latter, m. bearing means mounting the opposite end of the arm forpivotal movement on an axis coaxial with said driving shaft, and n. adriving drum on the driving shaft frictionally engaging the frictiondrive wheel for rotating the latter.
 4. The component testing apparatusof claim 1 wherein said drive and brake means are mounted within saidheadstock, and said friction drive wheel is mounted on said headstock.